[Dominators] Simplify templates

Summary: DominatorTreeBase and related classes used overcomplicated template machinery. This patch simplifies them and gets rid of DominatorTreeBaseTraits and DominatorTreeBaseByTraits, which weren't actually used outside the DomTree construction.

Reviewers: dberlin, sanjoy, davide, grosser

Reviewed By: dberlin, davide, grosser

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D35285

llvm-svn: 307953

include/llvm/IR/Dominators.h

@@ -37,19 +37,11 @@ extern template class DomTreeNodeBase<BasicBlock>;
 extern template class DominatorTreeBase<BasicBlock>;
 
 namespace DomTreeBuilder {
-extern template void Calculate<Function, BasicBlock *>(
-    DominatorTreeBaseByGraphTraits<GraphTraits<BasicBlock *>> &DT, Function &F);
+using BBDomTree = DominatorTreeBase<BasicBlock>;
 
-extern template void Calculate<Function, Inverse<BasicBlock *>>(
-    DominatorTreeBaseByGraphTraits<GraphTraits<Inverse<BasicBlock *>>> &DT,
-    Function &F);
+extern template void Calculate<BBDomTree, Function>(BBDomTree &DT, Function &F);
 
-extern template bool Verify<BasicBlock *>(
-    const DominatorTreeBaseByGraphTraits<GraphTraits<BasicBlock *>> &DT);
-
-extern template bool Verify<Inverse<BasicBlock *>>(
-    const DominatorTreeBaseByGraphTraits<GraphTraits<Inverse<BasicBlock *>>>
-        &DT);
+extern template bool Verify<BBDomTree>(const BBDomTree &DT);
 }  // namespace DomTreeBuilder
 
 using DomTreeNode = DomTreeNodeBase<BasicBlock>;

include/llvm/Support/GenericDomTree.h

@@ -43,25 +43,10 @@ namespace llvm {
 
 template <class NodeT> class DominatorTreeBase;
 
-namespace detail {
-
-template <typename GT> struct DominatorTreeBaseTraits {
-  static_assert(std::is_pointer<typename GT::NodeRef>::value,
-                "Currently NodeRef must be a pointer type.");
-  using type = DominatorTreeBase<
-      typename std::remove_pointer<typename GT::NodeRef>::type>;
-};
-
-} // end namespace detail
-
-template <typename GT>
-using DominatorTreeBaseByGraphTraits =
-    typename detail::DominatorTreeBaseTraits<GT>::type;
-
 /// \brief Base class for the actual dominator tree node.
 template <class NodeT> class DomTreeNodeBase {
   friend struct PostDominatorTree;
-  template <class N> friend class DominatorTreeBase;
+  friend class DominatorTreeBase<NodeT>;
 
   NodeT *TheBB;
   DomTreeNodeBase *IDom;
@@ -192,16 +177,16 @@ void PrintDomTree(const DomTreeNodeBase<NodeT> *N, raw_ostream &O,
 }
 
 namespace DomTreeBuilder {
-template <class NodeT>
+template <typename DomTreeT>
 struct SemiNCAInfo;
 
 // The calculate routine is provided in a separate header but referenced here.
-template <class FuncT, class N>
-void Calculate(DominatorTreeBaseByGraphTraits<GraphTraits<N>> &DT, FuncT &F);
+template <typename DomTreeT, typename FuncT>
+void Calculate(DomTreeT &DT, FuncT &F);
 
 // The verify function is provided in a separate header but referenced here.
-template <class N>
-bool Verify(const DominatorTreeBaseByGraphTraits<GraphTraits<N>> &DT);
+template <class DomTreeT>
+bool Verify(const DomTreeT &DT);
 }  // namespace DomTreeBuilder
 
 /// \brief Core dominator tree base class.
@@ -221,10 +206,13 @@ template <class NodeT> class DominatorTreeBase {
   mutable bool DFSInfoValid = false;
   mutable unsigned int SlowQueries = 0;
 
-  friend struct DomTreeBuilder::SemiNCAInfo<NodeT>;
-  using SNCAInfoTy = DomTreeBuilder::SemiNCAInfo<NodeT>;
+  friend struct DomTreeBuilder::SemiNCAInfo<DominatorTreeBase>;
 
  public:
+  static_assert(std::is_pointer<typename GraphTraits<NodeT *>::NodeRef>::value,
+                "Currently DominatorTreeBase supports only pointer nodes");
+  using NodeType = NodeT;
+  using NodePtr = NodeT *;
   explicit DominatorTreeBase(bool isPostDom) : IsPostDominators(isPostDom) {}
 
   DominatorTreeBase(DominatorTreeBase &&Arg)
@@ -612,35 +600,29 @@ public:
     using TraitsTy = GraphTraits<FT *>;
     reset();
 
-    if (!this->IsPostDominators) {
+    if (!IsPostDominators) {
       // Initialize root
       NodeT *entry = TraitsTy::getEntryNode(&F);
       addRoot(entry);
-
-      DomTreeBuilder::Calculate<FT, NodeT *>(*this, F);
     } else {
       // Initialize the roots list
       for (auto *Node : nodes(&F))
         if (TraitsTy::child_begin(Node) == TraitsTy::child_end(Node))
           addRoot(Node);
-
-      DomTreeBuilder::Calculate<FT, Inverse<NodeT *>>(*this, F);
     }
+
+    DomTreeBuilder::Calculate(*this, F);
   }
 
   /// verify - check parent and sibling property
-  bool verify() const {
-    return this->isPostDominator()
-           ? DomTreeBuilder::Verify<Inverse<NodeT *>>(*this)
-           : DomTreeBuilder::Verify<NodeT *>(*this);
-  }
+  bool verify() const { return DomTreeBuilder::Verify(*this); }
 
  protected:
   void addRoot(NodeT *BB) { this->Roots.push_back(BB); }
 
   void reset() {
     DomTreeNodes.clear();
-    this->Roots.clear();
+    Roots.clear();
     RootNode = nullptr;
     DFSInfoValid = false;
     SlowQueries = 0;

include/llvm/Support/GenericDomTreeConstruction.h

@@ -49,13 +49,13 @@ struct ChildrenGetter<NodePtr, true> {
   }
 };
 
-// Information record used by Semi-NCA during tree construction.
-template <typename NodeT>
+template <typename DomTreeT>
 struct SemiNCAInfo {
-  using NodePtr = NodeT *;
-  using DomTreeT = DominatorTreeBase<NodeT>;
+  using NodePtr = typename DomTreeT::NodePtr;
+  using NodeT = typename DomTreeT::NodeType;
   using TreeNodePtr = DomTreeNodeBase<NodeT> *;
 
+  // Information record used by Semi-NCA during tree construction.
   struct InfoRec {
     unsigned DFSNum = 0;
     unsigned Parent = 0;
@@ -524,23 +524,16 @@ struct SemiNCAInfo {
   }
 };
 
-template <class FuncT, class NodeT>
-void Calculate(DominatorTreeBaseByGraphTraits<GraphTraits<NodeT>> &DT,
-               FuncT &F) {
-  using NodePtr = typename GraphTraits<NodeT>::NodeRef;
-  static_assert(std::is_pointer<NodePtr>::value,
-                "NodePtr should be a pointer type");
-  SemiNCAInfo<typename std::remove_pointer<NodePtr>::type> SNCA;
+
+template <class DomTreeT, class FuncT>
+void Calculate(DomTreeT &DT, FuncT &F) {
+  SemiNCAInfo<DomTreeT> SNCA;
   SNCA.calculateFromScratch(DT, GraphTraits<FuncT *>::size(&F));
 }
 
-template <class NodeT>
-bool Verify(const DominatorTreeBaseByGraphTraits<GraphTraits<NodeT>> &DT) {
-  using NodePtr = typename GraphTraits<NodeT>::NodeRef;
-  static_assert(std::is_pointer<NodePtr>::value,
-                "NodePtr should be a pointer type");
-  SemiNCAInfo<typename std::remove_pointer<NodePtr>::type> SNCA;
-
+template <class DomTreeT>
+bool Verify(const DomTreeT &DT) {
+  SemiNCAInfo<DomTreeT> SNCA;
   return SNCA.verifyReachability(DT) && SNCA.VerifyLevels(DT) &&
          SNCA.verifyNCD(DT) && SNCA.verifyParentProperty(DT) &&
          SNCA.verifySiblingProperty(DT);

lib/IR/Dominators.cpp

@@ -63,22 +63,12 @@ bool BasicBlockEdge::isSingleEdge() const {
 template class llvm::DomTreeNodeBase<BasicBlock>;
 template class llvm::DominatorTreeBase<BasicBlock>;
 
-template void llvm::DomTreeBuilder::Calculate<Function, BasicBlock *>(
-    DominatorTreeBase<
-        typename std::remove_pointer<GraphTraits<BasicBlock *>::NodeRef>::type>
-        &DT,
-    Function &F);
-template void llvm::DomTreeBuilder::Calculate<Function, Inverse<BasicBlock *>>(
-    DominatorTreeBase<typename std::remove_pointer<
-        GraphTraits<Inverse<BasicBlock *>>::NodeRef>::type> &DT,
-    Function &F);
-template bool llvm::DomTreeBuilder::Verify<BasicBlock *>(
-    const DominatorTreeBase<
-        typename std::remove_pointer<GraphTraits<BasicBlock *>::NodeRef>::type>
-        &DT);
-template bool llvm::DomTreeBuilder::Verify<Inverse<BasicBlock *>>(
-    const DominatorTreeBase<typename std::remove_pointer<
-        GraphTraits<Inverse<BasicBlock *>>::NodeRef>::type> &DT);
+template void
+llvm::DomTreeBuilder::Calculate<DomTreeBuilder::BBDomTree, Function>(
+    DomTreeBuilder::BBDomTree &DT, Function &F);
+
+template bool llvm::DomTreeBuilder::Verify<DomTreeBuilder::BBDomTree>(
+    const DomTreeBuilder::BBDomTree &DT);
 
 bool DominatorTree::invalidate(Function &F, const PreservedAnalyses &PA,
                                FunctionAnalysisManager::Invalidator &) {